Ultra short wave system



Jan. 22, 1946. c. H. BROWN ULTRA SHORT WAVE SYSTEM Filed April 50, 1941 5 Sheets-Sheet l N 6% ESEQMQ QR W W m 5 i? NH E :2 WM w% w Y E FMQ ATTORNEY Jan. 22, 1946. c. H. BROWN ULTRA SHORT WAVE-SYSTEM Filed April 30, 1941 5 Sheets-Sheet 2 PIP-"MH- VSE kmxmbmk E mm M m R Y I 0 mm W N R m ig? E E H g 0 mg n R A M y B N ME 5 Sheets-Sheet 3 COMB/IV/IVG C. H. BROWN ULTRA SHORT WAVE SYSTEM Fly 4 Filed April 30, 1941 INVENTOR CHARLES IL BROWN BY ATTORNEY Jan. 22, 1946.

70 SIGN/4L Jan. 22, 1946. c, BROWN ULTRA SHORT WAVE sYsTEivl 5 Sheets-Sheet 4 Filed April 30, 1941 Flig- 5 *34 V I. r0 5mm 1 git m/pl/r 29 Y I {30 g T #4 34 rTmo o fizz v 29 6 EH51 Fl:9- 7 4o I A 4a 4/ 42 AMPL. [E 47 777M140 INVENTOR 46 CHARLES H. BROWN BY OUT/7W INPUT gun/WV ATTORNEY Jan. 22, 1946. c, H. BROWN 2,393,284

ULTRA SHORT WAVE SYSTEM Filed April 30, 1941 5 Sheets-Sheet 5 [QF AMPL INVENTOR .C'l/ARLES BROWN BY KZ/WV ATTORNEY Patented 'Jan. 22, 1946 ULTRA SHORT WAVE SYSTEM Charles H. Brown, Baldwin, Long Island, N. Y., assignor to Radio Corporation of America, a

corporation of Delaware Application April 30, 1941, Serial No. 391,063

15 Claims.

This invention relates to electron discharge devices and circuits therefor, for use particularly with ultra short waves below five meters, and is a continuation-in-part of my copending appli cation Serial No. 293,044, filed September 1, 1939, now United States Patent No. 2,280,026, granted April 14, 1942.

One of the objects of the present invention is to provide an improved-electron discharge device arrangement in which the electron transit-time effects are-minimized and which will function with relatively small losses at extremely high frequencies on the order of five meters to five centimeters.

Another object is to provide an improved electron discharge device circuit for obtaining a plurality of outputs of unrelated and/or related frequencies from a single electron beam.

A further object is to provide an electron discharge device and circuit therefor wherein a single electron beam is modulated by different carriers and there is obtained therefrom several outputs of different unrelated frequencies.

1 A still further object is to provide an electron discharge device arrangement including a pair of resonant tank circuits which are excited in succession by a single electron beam.

Other objects and various features of novelty will appear hereinafter from a reading of the following description.

Generally stated, the present invention consists of improvements in the ultra high frequency electron discharge device art, reference being made to the article by Dr. A. V. Haeff, entitled An Ultra High Frequency Power Amplifier of Novel Design, which appeared in Electronics for February, 1939, page 30 et seq., published by McGraw-Hill, Inc., for an understanding of the fundamental principles involved herein. The invention is useful in its application to oscillation generators, amplifiers, frequency converters and detectors, although not limited thereto.

A description of the invention follows in conjunction with drawings, given by way of exam-- A whereby a single electron beam traverses substantially the entire length of both tanks in succession;

Figs. 4 and 5 are modifications of the circuit employing the device of Fig. 3;

Fig. 6 shows the two tank circuits of Figs. 3, 4 and 5 compactly arranged in a preferred me chanical construction; and

Figs. 7 and 8 show other embodiments of the invention.

Throughout the figures of the drawings, the same or equivalent elements are designated by the. same reference numerals.

Referring to Fig. 1, there is shown an electrically quarter-wave concentric line tank circuit having an outer conductor I and an inner hollow conductor 2. both of which may be cylindrical' in cross-section, electrically coupled together by the conducting end plate 3. The conductors I and 2 are separated at one end by agap 6, there being provided a second tubular conductor 5 which is an aperture extension, so to speak, of the inner conductor 2 and coaxial therewith. This tubular extension 5 and the outer conductor i are connected by conducting plate 6. This arrangement provides a quarter-wave tank.

A suitable cathode 1 produces a beam of electrons whose density is modulated by a high frequency wave impressed by source 8 on grid 9 and which traverses the gap 4 before impinging upon the positively charged collector electrode Ill. It is preferred that collector electrode in be a hollow structure, conical, semi-circular, rectangular or otherwise, upon whose interior the electrons impinge. By means of magnetic focussing coil ii and electrostatic focussing electrode i2 the electron stream is caused to travel along the axis of the electron discharge device. Suitable electrodes i3, maintained at a positive potential relative to the cathode, serve to accelerate the electrons. These electrodes as well as the cathode 1, grid 9 and electron collector iii are positioned within an evacuated glass envelope M. The electron beam is broken up into a series of groups of electrons by the grid, and delivers high frequency power to the resonant concentric line tank I, 2, in the manner described in more detail in the article by Dr. A. V. Haefi, supra.

Power may therefore be abstracted from this tank I, 2 in any suitable manner.

In order to derive separate outputs from the electron discharge device there are provided a plurality of concentric line tank circuits l5, i6, l1, l8 spaced along the length of the tank i, 2 in the manner shown. The inner conductors of these additional tank circuits are each provided with a ring I! surrounding the electron beam for in succession.

obtaining by induction 2. charge in the tank circuit associated with the ring as the electrons pass through the ring. The rings l9 are suitably dimensioned to provide a proper time relation between the entry of an electron into the ring and its exit from the ring, it being preferred that the time of an electron to pass through any one ring correspond to one-half a period of the wave to which the particular tank associated with that ring is tuned. Each of the tanks l5, l5, .l1 and I8 are provided with separate output circuits 20, 2|, 22 .and 23, respectively, comprising loops inductively coupled to the inner conductors of the tanks. It will thus be seen that if the electron beam from cathode 1 is modulated with different carriers, indicated herein diagrammatically by source 8 and grid 9, or putting it another way, if the electron beam is modulated by the pick-ups from different shortwave stations (television or otherwise) and the tank circuits l5, l6, l1 and I8 suitably dimensioned or tuned to the frequencies of the carriers or intermediate frequencies derived therefrom, then different outputs can be taken from the loops 20, 2|, 22 and 23 to feed different receiving circuits. It is preferred, of course, that a local oscillator be employed in a separate circuit to provide the different intermediate frequencies to be impressed on grid 9, although the invention is not limited to such an arrangement. Where desired, the tanks l5, l8, l1 and i8 may be dimensioned to tune to different related frequencies (i. e., multiple harmonic frequencies) or even to the same frequency. In the latter instance there will be derived output currents from tanks l5, l6, I1, 18 of the same frequency but of difierent phase, which, if desired, can be combined in known manner to provide an amplified signal. From what is stated above, it will be apparent that the system of Fig. 1 provides a plurality of outputs obtainable from a single electron beam.

Fig. 2 shows a circuit arrangement somewhat similar to that of Fig. 1, except that there is additionally provided a local oscillator I80 coupled to a concentric tank circuit llll in order to modulate the electron stream of Fig. 2 before said stream passes through rings I9, is, so that where different pick-ups are initially impressed upon the electron stream, the individual tanks l to It, respectively, tuned to different intermediate frequencies, can derive energy of these frequencies from the electron stream; in this way the electron discharge device of the invention may function as a frequency converter. A suitable radio frequency input circuit I02 for varying the potential of ring l3 illustrates one way by which th electron stream may be velocity modulated between the rings l9, IQ of the auxiliary tank circuits.

Fig. 3 illustrates an amplifier arrangement wherein two quarter wave concentric line tanks 25 and 26, each substantially similar in construction to tank I, 2 of Fig. l, are arranged end to end in cascade, so that a single electron beam from the cathode 1 traverses the lengths of the inner conductors of both tanks, to excite them Tanks 25 and 26 may have the same or different dimensions. The gaps 4', 4' across the conductors of both concentric line tanks are positioned adjacent each other to reduce the transit time of the electrons exciting the two tank circuits, thereby maintaining the same electron grouping at bothgaps. An electrode 19 may be positioned between the two tanks 25 and 26 and maintained at a suitable potential employed as an amplifier or output stage.

for focussing the beam, anda single focussin coil ll may also surround the two gaps 4', 4'. The electron collector electrode l0 and the vari-. ous accelerating electrodes are all maintained at suitable positive potentials relative to the cathode I. Individual output circuits 21 and 28 are respectively coupled tothe two tank 25 and 25. If desired, these two outputs can be combined in a single combining circuit I03 to provide an amplified output, in which case both tanks 25 and 28 will have identical dimensions. The lines from loops 21 and 2-8 are adjustable by means of trombone slides 60 to provide the proper phase relations between the currents in 21 and 28 to make them add. In this way the circuit of Fig. 3 can be used to obtain a wider frequency band than is possible with only a single tank.

Fig. 4 shows a modification of the system of Fig. 3, wherein the first tank 25 is employed as an oscillator stage, while the second tank 26 is In Fig. 4 the output circuit 21 is utilized as a feedback circuit to modulate the electron stream, while the output circuit 28 extends to a. suitable utilization circuit. Trombone slides 61 serve to adjust the lengths of the feedback leads. If .it is desired to modulate the oscillations produced by the oscillator stage for transmission purposes,

there may be employed, by way of example, a

suitable frequency modulating circuit such as vacuum tube 29 to the control grid of which is coupled a. source of signals 30 and to whose screen grid and anode are coupled loops 3! and 32, respectively, electrostatically isolated from each other by a shield 33. In circuit with loop 3| there is provided a phase changer 34 so adjusted that tube 29 will draw either a leading or a lagging current, as desired, thus providing minimum amplitude modulation accompanying the desired frequency modulation.

By adjusting stage 25 to be an amplifier, as shown in Fig. 5', there will be obtained phase modulation effects. In Fig. 5, there is provided a. stable source of carrier oscillations 8', and it will be noted that the feed-back path 21 of Fig. 4 is eliminated. The phase modulated oscillator of Fig. 5 may be converted to a frequency modulation system while still employing the constant frequency generator 8' by predistorting the signal input 30 so that the output thereof varies in inverse proportion to the signal frequency. This may be accomplished by inserting an amplifier in the signal input lines having the desired characteristic.

Fig. 6 shows a preferred compact mechanical construction for the two tank circuits of Figs; 3, 4, and 5 which can be used in these figures. In Fig. 6 a single partition wall 35 separates the two tanks and further reduces the electron transit time between the gaps of the two tanks. If desired, the two tanks may have diiferent'dimensions, as indicated, the tank nearest the collector electrode l0 preferably having the smaller dimension in order to derive therefrom energy .of a harmonic frequency relative to the resonant frequency of the preceding tank. A coupling loop may be used when it is desired to couple' nate at a frequency preferably below one meter, let us say, for example, at a frequency in the range between centimeters and 30 centimeters. In the interior of the resonator and suitably spaced apart from each other are a. pair of dipole antenna elements 4!, 42 coupled respectively by way of lines 43 and 44 to the output and input of an oscillator 45 located externally of the resonator. Obviously, other coupling elements than dipoles can be used, such as circular loops. This oscillator is preferably mounted on the resonator to conserve space. A pair of leads 46 extend to a suitable load or utilization circuit. If desired, a suitable limiter may be coupled to leads 46 to insure a constant amplitude of oscillations in the output. By suitably spacing the dipole elements from the ends of the resonator 40, theresonatorwill be driven by the oscillator to obtain from leads 46 waves modulated as to frequency in accordance with signal modulations. One way of varying the dimensions of the resonator 40 is to make one end wall 48 of the resonator movable in response to voice currents. It should be understood, of course, that end wall 48 is directly connected, electrically, by contact with the side walls of the resonator. To achieve this, the movable end wall may include or consist of a magnetic diaphragm which is controllable by a solenoid 49, in turn coupled to the microphone 41. If desired, the stationary solenoid may be replaced by a moving coil scheme mounted in a magnetic field, the moving coil being responsive to the voice currents. This coil can be arranged in the air gap of a permanent or an electromagnet. It will thus be seen that the ultra high frequency field within the resonator 40 will be modulated at an audio frequency rate. The distance between the dipoles 4| and 42 need not be critical, although certain spacings will give better results than others. It will also be found that there will be maximum efficiency for certain spacings to be determined by trial and error between the dipoles and the end walls.

Fig. 8 illustrates another way of obtaining frequency modulation effects by means of an inductive output tube. In 'this figure, 50 represents an inductive output type coaxial resonator, generally of the type shown in Fig. 1, provided with a gap in its inner conductor and surrounded by a magnet coil II to provide a focussing effect for the electron stream of the vacuum tube l4. The resonator and tube are similar to the identically numbered elements of Figs. 1 and 2. A feed-back coil 51, coupled to the grid 9 and cathode 1, insures the production of continuous oscillations in thesystem. A permanent magnet diaphragm 52 in one end wall of the resonator 50, movable in response to audio signal modulations from microphone 41, serves to change the dimensions and hence the resonant frequency of the tank 50 and to modulate the frequency of oscillations produced ,in the system.

What is claimed is;

1. Electron discharge apparatus comprising first and second hollow resonators each of which has electron permeable confronting surfaces defining the boundary of a gap, means for projecting a stream of electrons through the interiors of said resonators in succession, including a cathode positioned outside the field of said first resonator and a collector electrode positioned outside the field of said second resonator and in a straight line with said cathode, said collector electrode gathering the electrons after they have passed through both of said resonators, and a grid electrode positioned between the gap of said" first resonator and said cathode, a source of energy coupled to said grid for modulating the density of said stream, a feed-back loop located in the interior of said first resonator and coupled to said rid, a loop located in the interior of said second resonator for deriving energy from said last resonator, and a load coupled to said last loop.

2. Electron discharge oscillator comprising a hollow'resonator having a gap, means for projecting a stream of electrons across said gap including a cathode and a collector electrode on opposite sides of said gap, a grid positioned between said cathode and said gap, 8. teed-back circuit coupling said resonator to said grid, and means for modulating the frequency of the oscillations produced by said oscillator comprising a multi-grid reactance .tube having its input grid electrode and cathode coupled to a signal input circuit and its screen grid electrode and anode coupled to loops located in the interior of said resonator.

3. In electronic apparatus having means for producing a. beam of electrons, the combination which includes a series of tubular elements of different dimensions arranged to be axially traversed by the beam, said elements being axially spacedto provide a plurality of gaps between them, a conductive structure concentrically surrounding each of said tubular elements and electrically connected thereto to form in combination therewith a resonant system, whereby said tubular elements comprise parts of different resonant systems, means for modulating the density of said beam of electrons prior to passage through one of said resonant systems, and means for abstracting energy from another of said resonant systems subsequently traversed by said beam.

4. In electronic apparatus having means for producing a beam of electrons, the combination which includes a series of tubular elements of different dimensions arranged to be axially traversed by the beam, said elements being axially spaced to provide a plurality of gaps between them, a conductive structure surrounding each of said tubular elements and electrically connected thereto to form in combination therewith a resonant system, whereby said tubular elements comprise parts of different resonant systems, means for abstracting energy from one of said resonant systems and feeding back said energy to modulate said beam of electrons, means for abstracting energy from another of said resonant systems subsequently traversed by said beam, and means in the interior of one of said resonators for varying the frequency thereof in accordance with signal modulation.

5. Electron discharge apparatus comprising first and second hollow resonators, means for projecting a stream of electrons through the interiors of said resonators in succession, including a cathode positioned outside the field of said first resonator and a collector electrode positioned outside the field of said second resonator and in a straight line with said cathode, said collector electrode gathering the electrons after they have passed through both of said resonators, a grid electrode in the form of a screen whose plane is at right angles to the path of travel of the stream of electrons and positioned between the gap of said first resonator and said cathode, a circuit coupled to said grid for modulating the density of said stream, said cathode, grid electrode and collector electrode being located within an evacuated container, a load coupled to said second resonator, a vacuum tube having a control electrode, a screen electrode and an anode, a source oi audio frequency signals coupled to said control electrode, a pair of conducting loops located in the interior of said first resonator, one of said loops being coupled to said anode and the other of said loops being coupledto said screen electrode. and a phase changer in circuit with one or said loops, whereby said apparatus constitutes an angular velocity modulation system.

6. Electron discharge apparatus comprising first and second hollow resonators each composed of a cylindrical hollow outer conductor and a coaxial hollow inner conductor, said outer conductors being continuations of one another, said inner conductors being located on the same straight line and separated from each other by gaps, said resonators being separated from each other by a single metallic partition extending at right angles to the directions of said outer and inner conductors from a point on said outer conductors to a point on said straight line, means for projecting a stream of electrons through the interiors of said resonators in succession, including a cathode positioned outside the field of said first resonator and a collector electrode positioned outside the field of said second resonator and in a straight line with said cathode, said collector electrode gathering the electrons after they have passed through both of said resonators, a grid electrode in the form of a screen whose plane is at right angles to the path of travel of the stream of electrons and positioned between the gap of said first resonator and said cathode, a circuit coupled to said grid for modulating the density of said stream, said cathode, grid electrode and collector electrode being located within an evacuated container, means coupled to said first resonator for producing angular velocity modulation eflects therein, and a load coupled to said second resonator.

I. In electronic apparatus having means for producing a stream of electrons, the combination which includes a hollow cavity resonator through which said stream passes, and a vacuum tube circuit for producing angular velocity modulation effects in said resonator, said vacuum tube including a pair of cold electrodes, said circuit including a pair of loops located in the interior of said resonator but electrostatically isolated from each other and coupledto diiferent cold electrodes of said vacuum tube, and a signal input circuit coupled to another electrode of said tube.

8. A modulation system comprising an electron bearn tube, a resonant chamber associated with said tube, means for modulatin the beam of electrons in said tube, coupling means entering the interior of and coupled to said resonant chamber, and means for altering the modulated electron beam into a diflerent form of modulation by varying the effective impedance of said coupling means, comprising a circuit for causin a reactive current to flow in said coupling means, and means for varying the amount of reactive current flowing in said coupling means in accordance with control voltages.

9. A modulation system comprising a modulation tube of the type employing a beam of elecasaases trons having means for modulating a characteristic thereof, a resonant chamber associated with said tube for regulating the frequency of operation of said tube. coupling means entering the interior of and coupled to said resonant chamber, and means for altering the modulation of said electron beam into a diiferent form of modulation by varying the effective impedance of said coupling means comprising a circuit for causing said coupling means to act as an effective reactance, and means to vary the amount of reactance presented by said coupling means in accordance with modulation potentials.

10. A modulation system comprisin a modulation tube having an electron beam passing therethrough, means for impressing a modulation on said beam, a resonant chamber associated with said tube for regulating the frequency of operation of said tube, coupling means entering the interior of and coupled to said resonant chamber, and means for altering the modulation of said beam into a diflerent form of modulation by varying. the effective impedance of said coupling means comprising a variable capacitive reactance coupled to said coupling means, and means for varying the capacity of said reactance at a modulation frequency rate.

11. In a. frequency or phase modulation system, electronic apparatus for producing a stream of electrons, a cavity resonator through the interior of which said stream. passes, said resonator having a gap through which said stream passes, a loop in the interior of said resonator, and connections from said loop to a source of signal modulation, and means including said loop and connections to produce angular velocity modulation effects in said system.

12. In a frequency or phase modulation system, an oscillation generator circuit including as a part thereof a resonator having uniformly distributed inductance and capacitance, said resonator having an outer conductor and a coaxial inner conductor, and a reactance tube modulator having a pair of cold electrodes individually coupled to said resonator by means of loops in the interior thereof, a connection from a source of signal modulation to an electrode of said modulator, the connections from said reactance tube to said resonator being so arranged as to produce angular velocity modulation efiects in said system.

13. In a frequency or phase modulation system, an oscillation generator circuit including as a part thereof a resonator having uniformly distributed inductance and capacitance, said resonator having an outer conductor and a coaxial inner conductor connected together at one end by a metallic plate, and a reactance tube modulator having a pair of cold electrodes individually coupled to said resonator by means of loops in the interior thereof located near said one. end of said resonator, a connection from a source of signal modulation to an electrode of said modulator, the connections from said reactance tube to said resonator being so arranged as to produce angular velocity modulation effects in said system.

14. In a frequency or phase modulation system, an oscillation generator circuit including as a part thereof a resonator having uniformly distributed inductance and capacitance, said resonator having an outer conductor and a coaxial inner condoctor, and a reactance'tube modulator having a pair of cold electrodes individually coupled to said resonator, one of said couplings comprising a loop in the interior of said resonator, a connection from a source 01' signal modulation to said modulator, the connections from said reactance tube to said resonator being so arranged as to produce angular velocity modulation effects in said system.

15. An oscillation generator comprising a hollow body resonator, means for producing a stream of electrons and for passing said stream through said resonator, means for modulating a characteristic of said stream, means for producing angular velocity modulation effects in said resonator comprising an element entering the interior of said resonator and in energy transfer relation to the electromagnetic field in said resonator, and signal modulation means coupled to said element.

CHARLES H. BROWN. 

